1. Field of the Invention
The present invention relates to a vehicle navigation apparatus that establishes a communication connection with a data transmission center via a communications device and obtains various kinds of information from the data transmission center. More particularly, the invention is directed to a vehicle navigation apparatus that can provide information about a new facility to a user quicker.
2. Description of the Related Art
A conventional vehicle navigation apparatus includes a map-data storage device for storing map data, such as a digital versatile disk (DVD) or a hard disk, a display device such as a liquid crystal display or the like, and a vehicle position detector for detecting a present position of a vehicle and a present traveling direction thereof, such as a gyro, a global positioning system (GPS) receiver, and a vehicle speed sensor or the like. In the navigation apparatus, map data including information on the present vehicle position is read from the map-data storage device, and based on the map data read, a map image covering the present vehicle position and its surroundings is drawn and displayed on the display device with a vehicle position (location) mark superimposed on the map image. The navigation apparatus can render the map image scrollable or the vehicle position mark movable with the map image fixed on a screen as the vehicle travels, thus allowing a user to understand the present traveling position of the vehicle at first glance.
Generally, the vehicle navigation apparatus has the function of route guidance that enables the user to easily travel an appropriate route to a desired destination without taking a wrong path. This route guidance function automatically searches for a route with the lowest cost connecting a starting point to the destination by simulated calculation such as the lateral search method or the Dijkstra method using the map data, and the resultant route searched for is stored as a guidance route. During traveling, the guidance route is displayed on a map by a thick line in a different color from that of the other road. Alternatively or additionally, when the vehicle is approaching an intersection on the guidance route where to turn right or left, an arrow representing a traveling direction beyond the intersection is drawn at the intersection on the map image. This guides the user to the destination.
The aforesaid cost is set in terms of a value obtained by multiplying a distance of a road by a constant depending on the width of the road, the type of the road (general road, or highway), the direction of a turn, namely a right turn or a left turn, or the like, or in terms of a time required for the vehicle to pass through the road on the basis of the distance thereof. Thus, the cost is a numeric value indicating the degree of propriety as the guidance route. Even if there are two roads with the same distance, the cost depends on, for example, whether the user makes use of a highway or not, or whether the user gives a high priority to the distance or the time.
In recent years, a vehicle navigation apparatus has been developed that establishes a communication connection with a data transmission center outside the vehicle using a communications device such as a portable telephone or the like, and obtains the latest map data and other information from the data transmission center. For example, a vehicle navigation apparatus has been released which obtains “valuable information about a shop”, together with the map data from the data transmission center, while announcing the “valuable information” by voice when the vehicle is approaching the shop. (See Pioneer Corporation Air Navi catalogue '02 Vol. 1.)
When some facilities of types (genres) associated with the user's favorites (for example, a convenience store, a CD shop, an amusement park, or the like) are newly set up, the user intends to know information about these facilities as quickly as possible. Thus, when a new facility appears, a vehicle navigation apparatus that provides information about the new facility to the user as quickly as possible is desired.